Large format near infrared HgCdTe 2Kx2K and 4Kx4K MBE arrays have reached a level of maturity which meets most of the specifications required for near infrared (NIR) astronomy. The only remaining problem is the persistence effect which is device specific and not yet fully under control. For ground based multi-object spectroscopy on 40 meter class telescopes larger pixels would be advantageous.<p> </p>For high speed near infrared fringe tracking and wavefront sensing the only way to overcome the CMOS noise barrier is the amplification of the photoelectron signal inside the infrared pixel by means of the avalanche gain. A readout chip for a 320x256 pixel HgCdTe eAPD array will be presented which has 32 parallel video outputs being arranged in such a way that the full multiplex advantage is also available for small sub-windows. In combination with the high APD gain this allows reducing the readout noise to the subelectron level by applying nondestructive readout schemes with subpixel sampling. Arrays grown by MOVPE achieve subelectron readout noise and operate with superb cosmetic quality at high APD gain. Efforts are made to reduce the dark current of those arrays to make this technology also available for large format focal planes of NIR instruments offering noise free detectors for deep exposures. The dark current of the latest MOVPE eAPD arrays is already at a level adequate for noiseless broad and narrow band imaging in scientific instruments.

HARMONI is the E-ELT’s first light visible and near-infrared integral field spectrograph. It will provide four different spatial scales, ranging from coarse spaxels of 60 × 30 mas best suited for seeing limited observations, to 4 mas spaxels that Nyquist sample the diffraction limited point spread function of the E-ELT at near-infrared wavelengths. Each spaxel scale may be combined with eleven spectral settings, that provide a range of spectral resolving powers (R ~3500, 7500 and 20000) and instantaneous wavelength coverage spanning the 0.5 – 2.4 &mu;m wavelength range of the instrument. In autumn 2015, the HARMONI project started the Preliminary Design Phase, following signature of the contract to design, build, test and commission the instrument, signed between the European Southern Observatory and the UK Science and Technology Facilities Council. Crucially, the contract also includes the preliminary design of the HARMONI Laser Tomographic Adaptive Optics system. The instrument’s technical specifications were finalized in the period leading up to contract signature. In this paper, we report on the first activity carried out during preliminary design, defining the baseline architecture for the system, and the trade-off studies leading up to the choice of baseline.

During the development of the VLT instrumentation program, ESO acquired considerable expertise in the area of infrared detectors, their testing and optimizing their performance. This can mainly be attributed to a very competent team and most importantly to the availability of a very well suited test facility, namely, IRATEC. This test facility was designed more than 15 years ago, specifically for 1K &times; 1K detectors such as the Aladdin device, with a maximum field of only 30 mm square. Unfortunately, this facility is no longer suited for the testing of the new larger format detectors that are going to be used to equip the future E-ELT instruments. It is projected that over the next 20 years, there will be of the order of 50-100 very large format detectors to be procured and tested for use with E-ELT first and second generation instruments and VLT third generation instruments. For this reason ESO has initiated the in-house design and construction of a dedicated new IR detector arrays test facility: the Facility for Infrared Array Testing (FIAT). It will be possible to mount up to four 60 mm square detectors in the facility, as well as mosaics of smaller detectors. It is being designed to have a very low thermal background such that detectors with 5.3 &mu;m cut-off material can routinely be tested. The paper introduces the most important use cases for which FIAT is designed: they range from performing routine performance measurements on acquired devices, optimization setups for custom applications (like spot scan intra-pixel response, persistence and surface reflectivity measurements), test of new complex operation modes (e.g. high speed subwindowing mode for low order sensing, flexure control, etc.) and the development of new tests and calibration procedures to support the scientific requirements of the E-ELT and to allow troubleshooting the unexpected challenges that arise when a new detector system is brought online. The facility is also being designed to minimize the downtime required to change to a new detector and then cool it down, ready for testing. The status of the opto-mechanical and cryogenic design is also described in detail, with particular emphasis on the technical solutions identified to fulfill the FIAT top level requirements. We will also describe how the FIAT project has been set-up as a training facility for the younger generation of engineers who are expected to take over the job from the experienced engineers and ensure that the lessons learnt in so many years of successful IR instrumentation projects at ESO are captured for this next generation.

The VLT second generation instrument SPHERE (Spectro-Polarimetric High-contrast Exoplanets Research) was commissioned in the Summer of 2014, and offered to the community in the Spring of 2015. SPHERE is a high contrast imager that exploits its three scientific channels in order to observe and discover young warm exoplanets in the glare of their host stars. The three scientific instrument are: ZIMPOL, a polarization analyzer and imager that works in the visible range of wavelength, IRDIS a dual band imager and spectro polarimetric Camera that works in the NIR range up to K band, and IFS, an integral field spectrograph working in the YJH band. Very important is the complementarity between IRDIS and IFS. The former has a larger Field of view (about 12 arcseconds) while the IFS push its examination very close to the central star (FoV ~ 1.7 arcsec). In one year of operational time a lot of very interesting scientific cases were investigated and very nice results were gathered. In this paper we would like to focus the attention on the high quality results and performances obtained with the IFS.

MATISSE is the second-generation mid-infrared spectrograph and imager for the Very Large Telescope Interferometer (VLTI) at Paranal. This new interferometric instrument will allow significant advances by opening new avenues in various fundamental research fields: studying the planet-forming region of disks around young stellar objects, understanding the surface structures and mass loss phenomena affecting evolved stars, and probing the environments of black holes in active galactic nuclei. As a first breakthrough, MATISSE will enlarge the spectral domain of current optical interferometers by offering the L and M bands in addition to the N band. This will open a wide wavelength domain, ranging from 2.8 to 13 &mu;m, exploring angular scales as small as 3 mas (L band) / 10 mas (N band). As a second breakthrough, MATISSE will allow mid-infrared imaging - closure-phase aperture-synthesis imaging - with up to four Unit Telescopes (UT) or Auxiliary Telescopes (AT) of the VLTI. Moreover, MATISSE will offer a spectral resolution range from R ∼ 30 to R ∼ 5000. Here, we present one of the main science objectives, the study of protoplanetary disks, that has driven the instrument design and motivated several VLTI upgrades (GRA4MAT and NAOMI). We introduce the physical concept of MATISSE including a description of the signal on the detectors and an evaluation of the expected performances. We also discuss the current status of the MATISSE instrument, which is entering its testing phase, and the foreseen schedule for the next two years that will lead to the first light at Paranal.

GRAVITY is a second generation instrument for the VLT Interferometer, designed for high-precision narrow-angle astrometry and phase-referenced interferometric imaging in the K-band. It will combine the AO corrected beams of the four VLT telescopes. In total, the GRAVITY instrument uses five eAPD detectors four for the infrared wavefront sensors of each telescope and one for the fringe tracker. In addition two Hawaii2RG arrays are installed, one for the acquisition camera and one for the spectrometer. The SAPHIRA eAPD array is a newly developed near-infrared detector with sub-electron noise performance at frame rates &gt; 1Kfps. For all seven detectors the ESO common controller, NGC, is used. This paper presents an overview and comparison of GRAVITY detector systems and their final performances at the telescope

The advent of low-dark-current eAPD arrays in the near infrared ushers in the possibility for photon-counting, high quantum efficiency detectors at these wavelengths. Such detectors would revolutionise the sensitivity of interferometry because near-infrared wavelengths are at the "sweet spot" between the corrupting effects of atmospheric seeing at shorter wavelengths and thermal noise at longer wavelengths. We report on laboratory experiments with cooled Selex Saphira detectors aimed at demonstrating photon-counting performance with these devices by exploiting enhanced avalanche gain and multiple non-destructive readouts. We explain the optimum modes for employing these detectors in interferometry.

We present an overview of the VISIR instrument after its upgrade and return to science operations. VISIR is the midinfrared imager and spectrograph at ESO’s VLT. The project team is comprised of ESO staff and members of the original VISIR consortium: CEA Saclay and ASTRON. The project plan was based on input from the ESO user community with the goal of enhancing the scientific performance and efficiency of VISIR by a combination of measures: installation of improved hardware, optimization of instrument operations and software support. The cornerstone of the upgrade is the 1k by 1k Si:As AQUARIUS detector array manufactured by Raytheon. In addition, a new prism spectroscopic mode covers the whole N-band in a single observation. Finally, new scientific capabilities for high resolution and high-contrast imaging are offered by sub-aperture mask and coronagraphic modes. In order to make optimal use of favourable atmospheric conditions, a water vapour monitor has been deployed on Paranal, allowing for real-time decisions and the introduction of a user-defined constraint on water vapour. During the commissioning in 2012, it was found that the on-sky sensitivity of the AQUARIUS detector was significantly below expectations. Extensive testing of the detector arrays in the laboratory and on-sky enabled us to diagnose the cause for the shortcoming of the detector as excess low frequency noise. It is inherent to the design chosen for this detector and cannot be remedied by changing the detector set-up. Since this is a form of correlated noise, its impact can be limited by modulating the scene recorded by the detector. After careful analysis, we have implemented fast (up to 4 Hz) chopping with field stabilization using the secondary mirror of the VLT. During commissioning, the upgraded VISIR has been confirmed to be more sensitive than the old instrument, and in particular for low-resolution spectroscopy in the N-band, a gain of a factor 6 is realized in observing efficiency. After overcoming several additional technical problems, VISIR is back in Science Operations since April 2015. In addition an upgrade of the IT infrastructure related to VISIR has been conducted in order to support burst-mode operations. Science Verification of the new modes was performed in Feb 2016. The upgraded VISIR is a powerful instrument providing close to background limited performance for diffraction-limited observations at an 8-m telescope. It offers synergies with facilities such as ALMA, JWST, VLTI and SOFIA, while a wealth of targets is available from survey works like WISE. In addition, it will bring confirmation of the technical readiness and scientific value of several aspects for future mid-IR instrumentation at Extremely Large Telescopes. We also present several lessons learned during the project.

ESO has now delivered or tested in-house, four new 5.3 μm cut-off H2RG detectors, for various projects, such as MATISSE for the VLTI and the upgrade project for CRIRES, the cryogenic high-resolution infrared echelle spectrograph for the VLT. The specified instruments have required the implementation of some of the more unusual read out options for these detectors, which may have already been used by other groups, for example, the line-reset-read and line-read-reset modes rather than the standard global reset mode. The detectors are also offered with both output speed options, that is, the standard slow, low noise readout and the faster, higher noise readout, where &gt; 10 frames/s are possible. In the process of building these detector systems and implementing these new options we have delved deeper into some of the lesser known features of these detectors and tried to characterize them more fully. It is important that these characteristics are well understood before delivery of the next generation of detectors for the ELTs where high speed and windowing options are required. We obtain very good performance at 2 Mpixel/s pixel speeds with less than 40 e- rms read noise, in all other aspects such as linearity, noise versus number of non-destructive reads and cross talk then the performance of the outputs is the same as slow speed operation. However, the high speed output stages are quite complex to operate, they need to be very well tuned and are prone to oscillation, if not set correctly. We will report on the best bias options to optimize their performance. Some stability issues are also seen with the slow outputs and this is also reported. Likewise we have observed differences between global reset and line reset for the detectors, manifested in a significant increase in detector full well for the line reset option, this also will be reported on. We have also determined that there may be signal induced by the detector readout clocking process for certain detector material or ROIC revision, at a significant level such that this may be the probable limiting factor of why Fowler sampling reaches a minimum noise value of approximately 3 e- rms for a small number of reads and then increases with further non-destructive reads.

GRAVITY is a second generation near-infrared VLTI instrument that will combine the light of the four unit or four auxiliary telescopes of the ESO Paranal observatory in Chile. The major science goals are the observation of objects in close orbit around, or spiraling into the black hole in the Galactic center with unrivaled sensitivity and angular resolution as well as studies of young stellar objects and evolved stars. In order to cancel out the effect of atmospheric turbulence and to be able to see beyond dusty layers, it needs infrared wave-front sensors when operating with the unit telescopes. Therefore GRAVITY consists of the Beam Combiner Instrument (BCI) located in the VLTI laboratory and a wave-front sensor in each unit telescope Coud&#233; room, thus aptly named Coud&#233; Infrared Adaptive Optics (CIAO). This paper describes the CIAO design, assembly, integration and verification at the Paranal observatory.

In 2007 ESO started a program at SELEX (now LEONARDO) to develop noiseless near infrared HgCdTe electron avalanche photodiode arrays (eAPD)[1][2][3]. This eAPD technology is only way to overcome the limiting CMOS noise barrier of near infrared sensors used for wavefront sensing and fringe tracking. After several development cycles of solid state engineering techniques which can be easily applied to the chosen growth technology of metal organic vapour phase epitaxy (MOVPE), the eAPD arrays have matured and resulted in the SAPHIRA arrays. They have a format of 320x256 pixels with a pitch of 24 &mu;m. They now offer an unmatched combination of sub-electron read noise at millisecond frame readout rates. The first generation of SAPHIRA arrays were only sensitive in H and K-band. With the removal of a wide bandgap buffer layer the arrays are now sensitive from &lambda;=0.8 &mu;m to 2.5 &mu;m with high quantum efficiency over the entire wavelength range. The high temperature anneal applied during the growth process produces material with superb cosmetic quality at an APD gain of over 600. The design of the SAPHIRA ROIC has also been revised and the new ME1000 ROIC has an optimized analogue chain and more flexible readout modes. The clock for the vertical shift register is now under external control. The advantage of this is that correlated-double-sampling and uncorrelated readout in the rolling shutter mode now have a duty cycle of 100% at the maximum frame rate. Furthermore, to reduce the readout noise rows can be read several times before and after row reset. Since the APD gain is sufficiently high that one photon produces many more electrons than the square root of kTC which is the charge uncertainty after reset, signals of one photon per exposure can be easily detected without the need for double correlated sampling. First results obtained with the fringe tracker in GRAVITY and the four SAPHIRA wavefront sensors installed in the CIAO adaptive optics systems of the four 8 meter telescopes of the VLTI have proven the unrivaled performance of the SAPHIRA eAPD technology. A future program is being assembled to develop eAPD arrays having a larger format of 1Kx1K capable of frame rates of 1.2 KHz. There are also good prospects to offer low dark current eAPD technology for large format science focal planes as well.

ESO has a very active on-going AO WFS detector development program to not only meet the needs of the current crop of instruments for the VLT, but also has been actively involved in gathering requirements, planning, and developing detectors and controllers/cameras for the instruments in design and being proposed for the E-ELT. <p> </p>This paper provides an overall summary of the AO WFS Detector requirements of the E-ELT instruments currently in design and telescope focal units. This is followed by a description of the many interesting detector, controller, and camera developments underway at ESO to meet these needs; a) the rationale behind and plan to upgrade the 240x240 pixels, 2000fps, “zero noise”, L3Vision CCD220 sensor based AONGC camera; b) status of the LGSD/NGSD High QE, 3e- RoN, fast 700fps, 1760x1680 pixels, Visible CMOS Imager and camera development; c) status of and development plans for the Selex SAPHIRA NIR eAPD and controller. <p> </p>Most of the instruments and detector/camera developments are described in more detail in other papers at this conference.

The only way to overcome the CMOS noise barrier of near infrared sensors used for wavefront sensing and fringe tracking is the amplification of the photoelectron signal inside the infrared pixel by means of the avalanche gain. In 2007 ESO started a program at Selex to develop near infrared electron avalanche photodiode arrays (eAPD) for wavefront sensing and fringe tracking. In a first step the cutoff wavelength was reduced from 4.5 micron to 2.5 micron in order to verify that the dark current scales with the bandgap and can be reduced to less than one electron/ms, the value required for wavefront sensing. The growth technology was liquid phase epitaxy (LPE) with annular diodes based on the loophole interconnect technology. The arrays required deep cooling to 40K to achieve acceptable cosmetic performance at high APD gain. The second step was to develop a multiplexer tailored to the specific application of the GRAVITY instrument wavefront sensors and the fringe tracker. The pixel format is 320x256 pixels. The array has 32 parallel video outputs which are arranged in such a way that the full multiplex advantage is available also for small subwindows. Nondestructive readout schemes with subpixel sampling are possible. This reduces the readout noise at high APD gain well below the subelectron level at frame rates of 1 KHz. The third step was the change of the growth technology from liquid phase epitaxy to metal organic vapour phase epitaxy (MOVPE). This growth technology allows the band structure and doping to be controlled on a 0.1&mu;m scale and provides more flexibility for the design of diode structures. The bandgap can be varied for different layers of Hg(<sub>1-x</sub>)Cd<sub>x</sub>Te. It is possible to make heterojunctions and apply solid state engineering techniques. The change to MOVPE resulted in a dramatic improvement in the cosmetic quality with 99.97 % operable pixels at an operating temperature of 85K. Currently this sensor is deployed in the 4 wavefront sensors and in the fringe tracker of the VLT instrument GRAVITY. Initial results will be presented. An outlook will be given on the potential of APD technology to be employed in large format near infrared science detectors. Several of the results presented here have also been shown to a different audience at the Scientific Detector Workshop in October 2013 in Florence but this paper has been updated with new results [1].

We present an overview of the VISIR upgrade project. VISIR is the mid-infrared imager and spectrograph at ESO’s
VLT. The project team is comprised of ESO staff and members of the original VISIR consortium: CEA Saclay and
ASTRON. The project plan is based on input from the ESO user community with the goal of enhancing the scientific
performance and efficiency of VISIR by a combination of measures: installation of improved hardware, optimization of
instrument operations and software support. The cornerstone of the upgrade is the 1k by 1k Si:As AQUARIUS detector
array (Raytheon) which has been carefully characterized in ESO’s IR detector test facility (modified TIMMI 2
instrument). A prism spectroscopic mode will cover the N-band in a single observation. New scientific capabilities for
high resolution and high-contrast imaging will be offered by sub-aperture mask (SAM) and phase-mask coronagraphic
(4QPM/AGPM) modes. In order to make optimal use of favourable atmospheric conditions a water vapour monitor has
been deployed on Paranal, allowing for real-time decisions and the introduction of a user-defined constraint on water
vapour. During the commissioning in 2012 it was found that the on-sky sensitivity of the AQUARIUS detector was
significantly below expectations and that VISIR was not ready to go back to science operations. Extensive testing of the
detector arrays in the laboratory and on-sky enabled us to diagnose the cause for the shortcoming of the detector as
excess low frequency noise (ELFN). It is inherent to the design chosen for this detector and can’t be remedied by
changing the detector set-up. Since this is a form of correlated noise its impact can be limited by modulating the scene
recorded by the detector. We have studied several mitigation options and found that faster chopping using the secondary
mirror (M2) of the VLT offers the most promising way forward. Faster M2 chopping has been tested and is scheduled
for implementation before the end of 2014 after which we plan to re-commission VISIR. In addition an upgrade of the IT
infrastructure related to VISIR is planned in order to support burst-mode operations. The upgraded VISIR will be a
powerful instrument providing close to background limited performance for diffraction-limited observations at an 8-m
telescope. It will offer synergy with facilities such as ALMA, JWST, VLTI and SOFIA, while a wealth of targets is
available from survey work (e.g. VISTA, WISE). In addition it will bring confirmation of the technical readiness and
scientific value of several aspects of potential mid-IR instrumentation at Extremely Large Telescopes.

HARMONI is a visible and near-infrared (0.47 to 2.45 &mu;m) integral field spectrometer, providing the E-ELT's core
spectroscopic capability, over a range of resolving powers from R (≡&lambda;/Δ&lambda;)~500 to R~20000. The instrument provides simultaneous spectra of ~32000 spaxels at visible and near-IR wavelengths, arranged in a &radic;2:1 aspect ratio contiguous field. HARMONI is conceived as a workhorse instrument, addressing many of the E-ELT’s key science cases, and will
exploit the E-ELT's scientific potential in its early years, starting at first light. HARMONI provides a range of spatial
pixel (spaxel) scales and spectral resolving powers, which permit the user to optimally configure the instrument for a
wide range of science programs; from ultra-sensitive to diffraction limited, spatially resolved, physical (via morphology),
chemical (via abundances and line ratios) and kinematic (via line-of-sight velocities) studies of astrophysical sources.
Recently, the HARMONI design has undergone substantial changes due to significant modifications to the interface with
the telescope and the architecture of the E-ELT Nasmyth platform. We present an overview of the capabilities of
HARMONI, and of its design from a functional and performance viewpoint.

MOONS will be the next near infrared fiber fed multi-object spectrograph for the Very Large Telescope, that will offer a
one thousand multiplexing capability and a simultaneous coverage of the wavelength range from 0.8 to 1.8 &mu;m.
With the aim of quantitatively i) assessing the instrument performances with respect to sensitivity and OH subtraction, ii)
blind-testing the 1D spectra extraction and calibration, provided by the data reduction pipeline, and iii) testing the
technical solutions adopted for reaching the outstanding instrument requirements, we have developed “Virtual
MOONS”, an end-to-end software simulator, which quantitatively computes high fidelity focal plane raw images,
emulating the output of the detector electronics.
Starting from an ideal photon image derived from the geometrical optics propagation and Point Spread Function (PSF)
variations computed by the ZEMAX optical design, the end-to-end optical budget is introduced along with the stray light
contributions, resulting in the expected photon counts impinging the detector pixels. Then the photon image plus photon
noise is converted to digital counts by means of a detailed detector simulation, including pixel-to-pixel response
variation, dark, bias, read-out noise, cosmetics, charge diffusion, flatness and read-out schemes. Critical points like fiber
differential response, PSF haloes and sky emission variations have been also taken into account.
The current status of this work is presented with an example simulated image and numerical results.

The 4MOST[1] instrument is a concept for a wide-field, fibre-fed high multiplex spectroscopic instrument facility on the
ESO VISTA telescope designed to perform a massive (initially &gt;25x106 spectra in 5 years) combined all-sky public
survey. The main science drivers are: Gaia follow up of chemo-dynamical structure of the Milky Way, stellar radial
velocities, parameters and abundances, chemical tagging; eROSITA follow up of cosmology with x-ray clusters of
galaxies, X-ray AGN/galaxy evolution to z~5, Galactic X-ray sources and resolving the Galactic edge;
Euclid/LSST/SKA and other survey follow up of Dark Energy, Galaxy evolution and transients. The surveys will be
undertaken simultaneously requiring: highly advanced targeting and scheduling software, also comprehensive data
reduction and analysis tools to produce high-level data products. The instrument will allow simultaneous observations of
~1600 targets at R~5,000 from 390-900nm and ~800 targets at R&lt;18,000 in three channels between ~395-675nm
(channel bandwidth: 45nm blue, 57nm green and 69nm red) over a hexagonal field of view of ~ 4.1 degrees. The initial
5-year 4MOST survey is currently expect to start in 2020. We provide and overview of the 4MOST systems: optomechanical,
control, data management and operations concepts; and initial performance estimates.

MATISSE is the mid-infrared spectrograph and imager for the Very Large Telescope Interferometer (VLTI) at Paranal. This second generation interferometry instrument will open new avenues in the exploration of our Universe. Mid-infrared interferometry with MATISSE will allow significant advances in various fundamental research fields: studies of disks around young stellar objects where planets form and evolve, surface structures and mass loss of stars in late evolutionary stages, and the environments of black holes in active galactic nuclei. MATISSE is a unique instrument. As a first breakthrough it will enlarge the spectral domain used by optical interferometry by offering the L &amp; M bands in addition to the N band, opening a wide wavelength domain, ranging from 2.8 to 13 μm on angular scales of 3 mas (L/M band) / 10 mas (N band). As a second breakthrough, it will allow mid-infrared imaging – closure-phase aperture-synthesis imaging – with up to four Unit Telescopes (UT) or Auxiliary Telescopes (AT) of the VLTI. MATISSE will offer various ranges of spectral resolution between R~30 to ~5000. In this article, we present some of the main science objectives that have driven the instrument design. We introduce the physical concept of MATISSE including a description of the signal on the detectors and an evaluation of the expected performance and discuss the project status. The operations concept will be detailed in a more specific future article, illustrating the observing templates operating the instrument, the data reduction and analysis, and the image reconstruction software.

GRAVITY is a second generation instrument for the VLT Interferometer, designed to enhance the near-infrared astrometric and spectro-imaging capabilities of VLTI. It will combine the AO corrected beams of the four VLT telescopes. The GRAVITY instrument uses a total of five eAPD detectors, four of which are for wavefront sensing and one for the Fringe tracker. In addition two Hawaii2RG are used, one for the acquisition camera and one for the spectrometer. A compact bath cryostat is used for each WFS unit, one for each of the VLT Unit Telescopes. Both Hawaii2RG detectors have a cutoff wavelength of 2.5 microns. A new and unique element of GRAVITY is the use of infrared wavefront sensors. For this reason SELEX-Galileo has developed a new high speed avalanche photo diode detector for ESO. The SAPHIRA detector, which stands for Selex Avalanche Photodiodes for Highspeed Infra Red Applications, has been already evaluated by ESO. At a frame rate of 1 KHz, a read noise of less than one electron can be demonstrated. A more detailed presentation about the performance of the SPAHIRA detector will be given at this conference 1. Each SAPHIRA detector is installed in an LN2 bath cryostat. The detector stage, filter wheel and optics are mounted on the cold plate of the LN2 vessel and enclosed by a radiation shield. All seven detector systems are controlled and read out by the standard ESO NGC controller. The NGC is a controller platform which can be adapted and customized for all infrared and optical detectors. This paper will discuss specific controller modifications implemented to meet the special requirements of the GRAVITY detector systems and give an overview of the GRAVITY detector systems and their performance.

4MOST is a wide-field, high-multiplex spectroscopic survey facility under development for the VISTA telescope of the European Southern Observatory (ESO). Its main science drivers are in the fields of galactic archeology, high-energy physics, galaxy evolution and cosmology. 4MOST will in particular provide the spectroscopic complements to the large
area surveys coming from space missions like Gaia, eROSITA, Euclid, and PLATO and from ground-based facilities like VISTA, VST, DES, LSST and SKA. The 4MOST baseline concept features a 2.5 degree diameter field-of-view with ~2400 fibres in the focal surface that are configured by a fibre positioner based on the tilting spine principle. The fibres feed two types of spectrographs; ~1600 fibres go to two spectrographs with resolution R&lt;5000 (&lambda;~390-930 nm) and
~800 fibres to a spectrograph with R&gt;18,000 (&lambda;~392-437 nm and 515-572 nm and 605-675 nm). Both types of spectrographs are fixed-configuration, three-channel spectrographs. 4MOST will have an unique operations concept in which 5 year public surveys from both the consortium and the ESO community will be combined and observed in parallel during each exposure, resulting in more than 25 million spectra of targets spread over a large fraction of the
southern sky. The 4MOST Facility Simulator (4FS) was developed to demonstrate the feasibility of this observing
concept. 4MOST has been accepted for implementation by ESO with operations expected to start by the end of 2020.
This paper provides a top-level overview of the 4MOST facility, while other papers in these proceedings provide more
detailed descriptions of the instrument concept[1], the instrument requirements development[2], the systems engineering implementation[3], the instrument model[4], the fibre positioner concepts[5], the fibre feed[6], and the spectrographs[7].

ESO has a very active on-going detector development program to not only meet the needs of the current crop of instruments for the VLT, but is also actively involved in gathering requirements and developing detectors for the challenging instruments being proposed and in design for the E-ELT. This paper provides an overall summary of the detector requirements of the various E-ELT instruments and the many interesting detector developments ESO is involved in to meet these needs. Most of these instruments and detector developments are described in more detail in other papers at this conference.

The success of the next generation of instruments for ELT class telescopes will depend upon improving the image quality by exploiting sophisticated Adaptive Optics (AO) systems. One of the critical components of the AO systems for the E-ELT has been identified as the optical Laser/Natural Guide Star WFS detector. The combination of large format, 1760&times;1680 pixels to finely sample the wavefront and the spot elongation of laser guide stars, fast frame rate of 700 frames per second (fps), low read noise (&lt; 3e-), and high QE (&gt; 90%) makes the development of this device extremely challenging. Design studies concluded that a highly integrated Backside Illuminated CMOS Imager built on High Resistivity silicon as the most likely technology to succeed. Two generations of the CMOS Imager are being developed: a) the already designed and manufactured NGSD (Natural Guide Star Detector), a quarter-sized pioneering device of 880&times;840 pixels capable of meeting first light needs of the E-ELT; b) the LGSD (Laser Guide Star Detector), the larger full size device. The detailed design is presented including the approach of using massive parallelism (70,400 ADCs) to achieve the low read noise at high pixel rates of ~3 Gpixel/s and the 88 channel LVDS 220Mbps serial interface to get the data off-chip. To enable read noise closer to the goal of 1e- to be achieved, a split wafer run has allowed the NGSD to be manufactured in the more speculative, but much lower read noise, Ultra Low Threshold Transistors in the unit cell. The NGSD has come out of production, it has been thinned to 12&mu;m, backside processed and packaged in a custom 370pin Ceramic PGA (Pin Grid Array). First results of tests performed both at e2v and ESO are presented.

ESO has already published data from a preliminary laboratory analysis on the new mid-IR detector, AQUARIUS, at the previous SPIE conference of 2012, held in Amsterdam<sup>2</sup>. This data analysis indicated that this new mid-IR Si:As IBC detector, from Raytheon Vision Systems, was an excellent astronomical detector when compared to previous generations of this detector type, specifically in terms of stability, read noise and cosmetic quality. Since that time, the detector has been deployed into the VISIR<sup>1</sup> instrument at the VLT, with very mixed performance results, especially when used with the telescope secondary mirror, to chop between two areas of sky to do background subtraction and at the same time when many frames are co-added to improve the signal to noise performance. This is the typical mode of operation for a mid-IR instrument on a ground based telescope. Preliminary astronomical data analysis indicated that the new detector was a factor of two to three times less sensitive in terms of its signal to noise per unit time performance when directly compared to the old DRS detector that AQUARIUS was designed to replace. To determine the reason for this loss of sensitivity, the instrument was removed from the telescope and not offered to the ESO user community. A detector testing campaign was then initiated in our laboratory to determine the reasons for this loss of sensitivity, assuming that it was an issue with the new detector itself. This paper reports on our latest laboratory measurements to determine the reasons for this loss of sensitivity. We specifically report on indirect measurements made to measure the quantum efficiency of the detector, which can be difficult to measure directly. We also report on a little known source of noise, called Excess Low Frequency Noise (ELFN). Detailed analysis and testing has confirmed that this ELFN is the reason for the loss of instrument sensitivity. This has been proven by a re-commissioning phase at the telescope with the instrument and the detector. A new set of observing parameters and observational regime have been developed to help to mitigate the ELFN. We outline a possible explanation for the source of the EFLN, learnt from a literature search and discussion with the manufacturer.

The Enhanced Resolution Imager and Spectrograph (ERIS) is the next-generation adaptive optics near-IR imager and
spectrograph for the Cassegrain focus of the Very Large Telescope (VLT) Unit Telescope 4, which will soon make full
use of the Adaptive Optics Facility (AOF). It is a high-Strehl AO-assisted instrument that will use the Deformable
Secondary Mirror (DSM) and the new Laser Guide Star Facility (4LGSF). The project has been approved for
construction and has entered its preliminary design phase. ERIS will be constructed in a collaboration including the Max-
Planck Institut für Extraterrestrische Physik, the Eidgenössische Technische Hochschule Zürich and the Osservatorio
Astrofisico di Arcetri and will offer 1 - 5 &mu;m imaging and 1 - 2.5 &mu;m integral field spectroscopic capabilities with a high
Strehl performance. Wavefront sensing can be carried out with an optical high-order NGS Pyramid wavefront sensor, or
with a single laser in either an optical low-order NGS mode, or with a near-IR low-order mode sensor. Due to its highly
sensitive visible wavefront sensor, and separate near-IR low-order mode, ERIS provides a large sky coverage with its 1’
patrol field radius that can even include AO stars embedded in dust-enshrouded environments. As such it will replace,
with a much improved single conjugated AO correction, the most scientifically important imaging modes offered by
NACO (diffraction limited imaging in the J to M bands, Sparse Aperture Masking and Apodizing Phase Plate (APP)
coronagraphy) and the integral field spectroscopy modes of SINFONI, whose instrumental module, SPIFFI, will be
upgraded and re-used in ERIS. As part of the SPIFFI upgrade a new higher resolution grating and a science detector
replacement are envisaged, as well as PLC driven motors. To accommodate ERIS at the Cassegrain focus, an extension
of the telescope back focal length is required, with modifications of the guider arm assembly. In this paper we report on
the status of the baseline design. We will also report on the main science goals of the instrument, ranging from exoplanet
detection and characterization to high redshift galaxy observations. We will also briefly describe the SINFONI-SPIFFI
upgrade strategy, which is part of the ERIS development plan and the overall project timeline.

SPHERE is an extrasolar planet imager whose goal is to detect giant extrasolar planets in the vicinity of bright stars and
to characterize them through spectroscopic and polarimetric observations. It is a complete system with a core made of an
extreme-Adaptive Optics (AO) turbulence correction, a pupil tracker and NIR and Visible coronagraph devices. At its
back end, a differential dual imaging camera and an integral field spectrograph (IFS) work in the Near Infrared (NIR)
(0.95 &le;&lambda;&le;2.32 &mu;m) and a high resolution polarization camera covers the visible (0.6 &le;&lambda;&le;0.9 &mu;m). The IFS is a low resolution spectrograph (R~50) operates in the near IR (0.95&le;&lambda;&le;1.6 &mu;m), an ideal wavelength range for the detection of planetary features, over a field of view of about 1.7 x 1.7 square arcsecs. Form spectra it is possible to reconstruct monochromatic images with high contrast (10<sup>-7</sup>) and high spatial resolution, well inside the star PSF. In this paper we describe the IFS, its calibration and the results of several performance which IFS underwent. Furthermore, using the IFS characteristics we give a forecast on the planetary detection rate.

KMOS is a multi-object near-infrared integral field spectrograph built by a consortium of UK and German institutes for
the ESO Paranal Observatory. We report on the on-sky performance verification of KMOS measured during three
commissioning runs on the ESO VLT in 2012/13 and some of the early science results.

This paper reports on the status of advanced infrared detectors exploiting Metal-Organic Vapour Phase Epitaxy (MOVPE) grown HgCdTe on GaAs at Selex ES. MOVPE has the maturity and flexibility to enable 3<sup>rd</sup> generation devices to be custom engineered to achieve small pixels, higher operating temperature, high sensitivity and tailored spectral response. The MOVPE technology has now been exploited in the latest development of avalanche photodiodes and single photon imaging is reported. In support of this the latest ROICs have been designed to be compatible with APD operation.

The Enhanced Resolution Imager and Spectrograph (ERIS) is the next-generation instrument planned for the Very Large
Telescope (VLT) and the Adaptive Optics Facility (AOF)<sup>1</sup>. It is an AO assisted instrument that will make use of the
Deformable Secondary Mirror and the new Laser Guide Star Facility (4LGSF), and it is designed for the Cassegrain
focus of the telescope UT4. The project just concluded its conceptual design phase and is awaiting formal approval to
continue to the next phase. ERIS will offer 1-5 μm imaging and 1-2.5 &mu;m integral field spectroscopic capabilities with
high Strehl performance. As such it will replace, with much improved single conjugated AO correction, the most
scientifically important and popular observing capabilities currently offered by NACO<sup>2</sup> (diffraction limited imaging in JM
band, Sparse Aperture Masking and APP coronagraphy) and by SINFONI<sup>3</sup>, whose instrumental module, SPIFFI, will
be re-used in ERIS. The Cassegrain location and the performance requirements impose challenging demands on the
project, from opto-mechanical design to cryogenics to the operational concept. In this paper we describe the baseline
design proposed for ERIS and discuss these technical challenges, with particular emphasis on the trade-offs and the
novel solutions proposed for building ERIS.

The 4MOST consortium is currently halfway through a Conceptual Design study for ESO with the aim to develop a wide-field ( &lt; 3 square degree, goal &lt; 5 square degree), high-multiplex ( &lt; 1500 fibres, goal 3000 fibres) spectroscopic survey facility for an ESO 4m-class telescope (VISTA). 4MOST will run permanently on the telescope to perform a 5 year public survey yielding more than 20 million spectra at resolution R∼5000 (&lambda;=390–1000 nm) and more than 2 million spectra at R~20,000 (395–456.5 nm and 587–673 nm). The 4MOST design is especially intended to complement three key all-sky, space-based observatories of prime European interest: Gaia, eROSITA and Euclid. Initial design and performance estimates for the wide-field corrector concepts are presented. Two fibre positioner concepts are being considered for 4MOST. The first one is a Phi-Theta system similar to ones used on existing and planned facilities. The second one is a new R-Theta concept with large patrol area. Both positioner concepts effectively address the issues of fibre focus and pupil pointing. The 4MOST spectrographs are fixed configuration two-arm spectrographs, with dedicated spectrographs for the high- and low-resolution fibres. A full facility simulator is being developed to guide trade-off decisions regarding the optimal field-of-view, number of fibres needed, and the relative fraction of high-to-low resolution fibres. The simulator takes mock catalogues with template spectra from Design Reference Surveys as starting point, calculates the output spectra based on a throughput simulator, assigns targets to fibres based on the capabilities of the fibre positioner designs, and calculates the required survey time by tiling the fields on the sky. The 4MOST consortium aims to deliver the full 4MOST facility by the end of 2018 and start delivering high-level data products for both consortium and ESO community targets a year later with yearly increments.

We present an overview of the VISIR upgrade project. VISIR is the mid-infrared imager and spectrograph at ESO’s
VLT. The project team is comprised of ESO staff and members of the original VISIR consortium: CEA Saclay and
ASTRON. The project plan is based on input from the ESO user community with the goal of enhancing the scientific
performance and efficiency of VISIR by a combination of measures: installation of improved hardware, optimization of
instrument operations and software support. The cornerstone of the upgrade is the 1k by 1k Si:As Aquarius detector
array (Raytheon) which has demonstrated very good performance (sensitivity, stability) in the laboratory IR detector test
facility (modified TIMMI 2 instrument). A prism spectroscopic mode will cover the N-band in a single observation. New
scientific capabilities for high resolution and high-contrast imaging will be offered by sub-aperture mask (SAM) and
phase-mask coronagraphic (4QPM/AGPM) modes. In order to make optimal use of favourable atmospheric conditions a
water vapour monitor has been deployed on Paranal, allowing for real-time decisions and the introduction of a userdefined
constraint on water vapour. Improved pipelines based on the ESO Reflex concept will provide better support to
astronomers. The upgraded VISIR will be a powerful instrument providing background limited performance for
diffraction-limited observations at an 8-m telescope. It will offer synergy with facilities such as ALMA, JWST, VLTI
and SOFIA, while a wealth of targets is available from survey work (e.g. VISTA, WISE). In addition it will bring
confirmation of the technical readiness and scientific value of several aspects of potential mid-IR instrumentation at
Extremely Large Telescopes. The intervention on VISIR and installation of hardware has been completed in July and
commissioning will take place during July and August. VISIR is scheduled to be available to the users starting Oct 2012.

ESO has recently funded the development of the AQUARIUS detector at Raytheon Vision Systems, a new mega-pixel
Si:As Impurity Band Conduction array for use in ground based astronomical applications at wavelengths between 3 – 28
&mu;m. The array has been designed to have low noise, low dark current, switchable gain and be read out at very high frame
rates. It has 64 individual outputs capable of pixel read rates of 3MHz, implying continuous data-rates in excess of 300
Mbytes/second. It is scheduled for deployment into the VISIR instrument at the VLT in 2012, for next generation VLTI
instruments and base-lined for METIS, the mid-IR candidate instrument for the E-ELT. A new mid-IR test facility has
been developed for AQUARIUS detector development which includes a low thermal background cryostat, high speed
cryogenic pre-amplification and high speed data acquisition and detector operation at 5K. We report on all the major
performance aspects of this new detector including conversion gain, read noise, dark generation rate, linearity, well
capacity, pixel operability, low frequency noise, persistence and electrical cross-talk. We describe the many possible
readout modes of this detector and their application. We also report on external issues with the operation of these
detectors at such low temperatures. Finally we report on the electronic developments required to operate such a detector
at the required high data rates and in a typical mid-IR instrument.

The success of the next generation of instruments for 8 to 40-m class telescopes will depend upon improving the image
quality (correcting the distortion caused by atmospheric turbulence) by exploiting sophisticated Adaptive Optics (AO)
systems. One of the critical components of the AO systems for the E-ELT has been identified as the Laser/Natural Guide
Star (LGS/NGS) WaveFront Sensing (WFS) detector. The combination of large format, 1760x1680 pixels to finely
sample (84x84 sub-apertures) the wavefront and the spot elongation of laser guide stars, fast frame rate of 700 (up to
1000) frames per second, low read noise (&lt; 3e-), and high QE (&gt; 90%) makes the development of such a device
extremely challenging. Design studies by industry concluded that a thinned and backside-illuminated CMOS Imager as
the most promising technology. This paper describes the multi-phased development plan that will ensure devices are
available on-time for E-ELT first-light AO systems; the different CMOS pixel architectures studied; measured results of
technology demonstrators that have validated the CMOS Imager approach; the design explaining the approach of
massive parallelism (70,000 ADCs) needed to achieve low noise at high pixel rates of ~3 Gpixel/s ; the 88 channel
LVDS data interface; the restriction that stitching (required due to the 5x6cm size) posed on the design and the solutions
found to overcome these limitations. Two generations of the CMOS Imager will be built: a pioneering quarter sized
device of 880x840 pixels capable of meeting first light needs of the E-ELT called NGSD (Natural Guide Star Detector);
followed by the full size device, the LGSD (Laser Guide Star Detector). Funding sources: OPTICON FP6 and FP7 from
European Commission and ESO.

The performance of the current high speed near infrared HgCdTe sensors operating in fringe trackers, wavefront sensors
and tip-tilt sensors is severely limited by the noise of the silicon readout interface circuit (ROIC), even if state-of-the- art
CMOS designs are used. A major improvement can only be achieved by the amplification of the photoelectron signal
directly at the point of absorption by means of avalanche gain inside the infrared pixel. Unlike silicon, HgCdTe offers
noiseless avalanche gain. This has been verified with the LPE grown 320x256 pixel &lambda;<sub>c</sub>=2.5 μm HgCdTe eAPD arrays
from SELEX both on a prototype ROIC called SWALLOW and on a newly developed ROIC, specifically designed for
AO applications, called SAPHIRA. The novel features of the new SAPHIRA ROIC, which has 32 parallel video channels
operating at 5 MHz, will be described, together with the new high speed NGC data acquisition system. Performance
results will be discussed for both ROICs. The LPE material on the SWALLOW prototype was excellent and allowed
operation at an APD gain as high as 33. Unfortunately, the LPE material of the first devices on the SAPHIRA ROIC suffers
from problems which are now understood. However, due to the excellent performance of the SAPHIRA ROIC even
with the limitations of present HgCdTe material, it is possible with simple double correlated sampling to detect test patterns
with signal levels of 1 electron. An outlook will be given on further developments of heterojunctions grown by
MOVPE, which eventually may replace eAPD arrays grown by LPE.

SPHERE is an exo-solar planet imager, which goal is to detect giant exo-solar planets in the vicinity of bright stars and
to characterize them through spectroscopic and polarimetric observations. It is a complete system with a core made of an
extreme-Adaptive Optics (AO) turbulence correction, pupil tracker and NIR and Visible coronagraph devices. At its
back end, a differential dual imaging camera and an integral field spectrograph (IFS) work in the Near Infrared (NIR) Y,
J, H and Ks bands (0.95&le;&lambda;&le;2.32 &mu;m) and a high resolution polarization camera covers the visible (0.6&le;&lambda;&le;0.9 &mu;m). The
IFS is a low resolution spectrograph (R~50) which works in the near IR (0.95&le;&lambda;&le;1.6 &mu;m), an ideal wavelength range for
the detection of planetary features. The IFS is based on a new conception microlens array (BIGRE) of 145X145 lenslets
designed to reduce as low as possible the contrast. The IFU will cover a field of view of about 1.7 x 1.7 square arcsecs
reaching a contrast of 10<sup>-7</sup>, giving an high contrast and high spatial resolution "imager" able to search for planet well
inside the star PSF. In the last year it has been integrated onto the huge optical bench of SPHERE and fully tested.

KMOS is a multi-object near-infrared integral field spectrograph being built by a consortium of UK and German
institutes. We report on the final integration and test phases of KMOS, and its performance verification, prior to
commissioning on the ESO VLT later this year.

MATISSE is a mid-infrared spectro-interferometer combining the beams of up to four Unit Telescopes or Auxiliary
Telescopes of the Very Large Telescope Interferometer (VLTI) of the European Southern Observatory.
MATISSE will constitute an evolution of the two-beam interferometric instrument MIDI. New characteristics present in
MATISSE will give access to the mapping and the distribution of the material, the gas and essentially the dust, in the
circumstellar environments by using the mid-infrared band coverage extended to L, M and N spectral bands. The four
beam combination of MATISSE provides an efficient uv-coverage: 6 visibility points are measured in one set and 4
closure phase relations which can provide aperture synthesis images in the mid-infrared spectral regime.
We give an overview of the instrument including the expected performances and a view of the Science Case. We present
how the instrument would be operated. The project involves the collaborations of several agencies and institutes: the
Observatoire de la Côte d’Azur of Nice and the INSU-CNRS in Paris, the Max Planck Institut für Astronomie of
Heidelberg; the University of Leiden and the NOVA-ASTRON Institute of Dwingeloo, the Max Planck Institut für
Radioastronomie of Bonn, the Institut für Theoretische Physik und Astrophysik of Kiel, the Vienna University and the
Konkoly Observatory.

Raytheon Vision Systems (RVS) has developed a family of high performance large format infrared (IR) detector arrays
whose detectors are most effective for the detection of long and very long wavelength IR energy. This paper describes
the evolution of the present state of the art one mega-pixel Si: As Impurity Band Conduction (IBC) arrays toward a four
mega-pixel array that is desired by the astronomy community. Raytheon's Aquarius-1k, developed in collaboration with
ESO, is a 1024 &times; 1024 pixel high performance array with a 30 &#956;m pitch that features high quantum efficiency IBC
detectors, low noise, low dark current, and on-chip clocking for ease of operation. Since the Aquarius-1k array was
designed primarily for ground-based astronomy applications, it incorporates selectable gains and a large well capacity
among its other features. Raytheon, in collaboration with JAXA (Japan Aerospace Exploration Agency), is also
designing a 2048 &times; 2048 pixel high performance array with a 25 &#956;m pitch. This 2k &times; 2k readout circuit will be based on
the successful design used for the on the Mid-Infrared Instrument (MIRI) aboard the James Webb Space Telescope
(JWST). It will feature high quantum efficiency IBC detectors, low noise, low dark current, and on-chip clocking for
ease of operation. This version will also incorporate flight qualified packaging to support space-based astronomy
applications. Previous generations of RVS IBC detectors have flown on several platforms, including NASA's Spitzer
Space Telescope and Japan's Akari Space Telescope.

SPHERE is a planet hunting instrument for the VLT 8m telescope in Chile whose prime objective is the discovery and
characterization of young Jupiter-sized planets outside of the solar system. It is a complex instrument, consisting of an
extreme Adaptive Optics System (SAXO), various coronagraphs, an infrared differential imaging camera (IRDIS), an
infrared integral field spectrograph (IFS) and a visible differential polarimeter (ZIMPOL). The performance of the IRDIS
camera is directly related to various wavefront error budgets of the instrument, in particular the differential aberrations
occurring after separation of the two image beams. We report on the ongoing integration and testing activities in terms of
optical, mechanical, and cryo-vacuum instrument parts. In particular, we show results of component level tests of the
optics and indicate expected overall performance in comparison with design-level budgets. We also describe the plans
for instrumental performance and science testing of the instrument, foreseen to be conducted during coming months.

Raytheon Vision Systems (RVS) has developed a family of high performance large format infrared detector arrays
whose detectors are most effective for the detection of long and very long wavelength infrared energy. This paper
describes the state of the art in mega-pixel Si:As Impurity Band Conduction (IBC) arrays and relevant system
applications that offers unique off-the-shelf solutions to the astronomy community. Raytheon's Aquarius-1k, developed
in collaboration with ESO, is a 1024 &times; 1024 pixel high performance array with a 30&mu;m pitch that features high quantum
efficiency IBC detectors, low noise, low dark current, and on-chip clocking for ease of operation. This large format array
was designed for ground-based astronomy applications but lends itself for space based platforms too. The detector has
excellent sensitivity out to 27&mu;m wavelength. The readout circuit has several programmable features such as low gain for
a well capacity of 11 &times; 10<sup>6</sup>e-, high gain for a well capacity of 10<sup>6</sup>e- and a programmable number of outputs (16 or 64).
Programmable integration time and integration modes, like snapshot, rolling and non-destructive integrations, allow the
Aquarius to be used for a wide variety of applications and performance. A very fast full frame rate of 120Hz is achieved
with 64 outputs (32 outputs per side) and a programmable centered windowing will accommodate a wide range of
readout rates. The multiplexer and packaging design utilizes two alignment edges on the SCA which can be butted on
two sides for expansion to 2k &times; 1k and wider focal planes. Data is shown on several focal plane arrays to demonstrate
that very low noise and high quantum efficiency performance has been achieved. This array leverages over thirty years
of experience in both ground and space based astronomy sensor applications. The technology has been successfully
demonstrated on programs such as NASA's Spitzer Space Telescope and Japan's Akari Space Telescope, and will be
used on the Mid-Infrared Instrument (MIRI) aboard the James Webb Space Telescope (JWST).

The European Southern Observatory (ESO) is preparing to upgrade VISIR, the mid-IR imager and spectrograph at the
VLT. The project team is comprised of ESO staff and members of the original consortium that built VISIR: CEA Saclay
and ASTRON. The goal is to enhance the scientific performance of VISIR and to facilitate its use by the ESO
community. In order to capture the needs of the user community, we collected input from the users by means of a webbased
questionnaire. In line with the results of the internal study and the input from the user community, the upgrade
plan calls for a combination measures: installation of improved hardware, optimization of instrument operations and
software support. The limitations of the current detector (sensitivity, cosmetics, artifacts) have been known for some
time and a new 1k x 1k Si:As Aquarius array (Raytheon) will be the cornerstone of the VISIR upgrade project. A
modified spectroscopic mode will allow covering the N-band in a single observation. Several new scientific modes (e.g.,
polarimetry, coronagraphy) will be implemented on a best effort basis. In addition, the VISIR operational scheme will be
enhanced to ensure that optimal use of the observing conditions will be made. Specifically, we plan to provide a means
to monitor precipitable water vapour (PWV) and enable the user to specify it as a constraint set for service mode
observations. In some regions of the mid-IR domain, the amount of PWV has a fundamental effect on the quality of a
given night for mid-IR astronomy. The plan also calls for full support by ESO pipelines that will deliver science-ready
data products. Hence the resulting files will provide physical units and error information and all instrumental signatures
will have been removed. An upgraded VISIR will be a powerful instrument providing diffraction-limited performance at
an 8-m telescope. Its improved performance and efficiency as well as new science capabilities will serve the needs of the
ESO community but will also offer synergy with various other facilities such as ALMA, JWST, VLTI and SOFIA. A
wealth of targets for detailed study will be available from survey work done by VISTA and WISE. Finally, the upgraded
VISIR will also serve as a pathfinder for potential mid-IR instrumentation at the European Extremely Large Telescope
(E-ELT) in terms of technology as well as operations.

ESO has begun an ambitious mid-IR detector program with the funded development of a new Raytheon detector
(AQUARIUS) and the further development of instruments to use 5 &#956;m cut-off material Teledyne HAWAII-2RG
detectors. Both these detector types are capable of extremely high readout speeds, through multiple readout ports,
resulting in data rates in excess of 250 Mbytes/s. This has required further development of our new detector controller
system (NGC) to allow it to operate at these very high pixel data rates. This has also entailed the development of new
high speed pre-amplifiers which can operate at 60K to allow us to drive the long cable runs typical of an astronomical
instrument. We report on the development and performance of our new higher speed NGC systems with particular regard
to the operation of a Hawaii-2RG detector configured to use its high speed readout stages. We will present data on the
performance of such at device, configured to operate in both slow and fast readout modes, with particular regard to noise
versus pixel speed and also the optimization of the voltages.

Teledyne Imaging Sensors (TIS) has developed a CMOS device known as the SIDECAR application-specific integrated
circuit (ASIC). This single chip provides all the functionality of FPA drive electronics to operate visible and infrared
imaging detectors with a fully digital interface. A Teledyne 2K &times;2K silicon PIN diode array hybridized to a Hawaii-2RG
multiplexer, the Hybrid Visible Silicon Imager (HyViSI) was read out with the ESO standard IR detector controller
IRACE, which delivers detector limited performance. We have tested the H2RG HyViSI detector with the TIS
SIDECAR ASIC in 32 channel readout mode at cryogenic temperatures. The SIDECAR has been evaluated down to 105
Kelvin operating temperature and performance results have been compared to those obtained with external electronics.
Furthermore ESO has developed its own interface card to replace the JADE USB card provided by Teledyne. The ASIC
controller is now being embedded in the ESO standard VLT hard and software environment. This paper provides an
update on the recent development of the new ESO ASIC interface card. We find that the SIDECAR ASIC provides
performance equal to external electronics.

The most promising way to overcome the CMOS noise barrier of infrared AO sensors is the amplification of the photoelectron
signal directly at the point of absorption inside the infrared pixel by means of the avalanche gain. HgCdTe eAPD
arrays with cut off wavelengths of &#955;<sub>c</sub> ~2.64 &#956;m produced by SELEX-Galileo have been evaluated at ESO. The arrays
were hybridized to an existing non-optimized ROIC developed for laser gated imaging which has a format of 320&times;256
pixels and four parallel video outputs. The avalanche gain makes it possible to reduce the read noise to &lt; 7 e rms. The
dark current requirements of IR wavefront sensing are also met.

X-shooter is the first second-generation instrument newly commissioned a the VLT. It is a high efficiency single
target intermediate resolution spectrograph covering the range 300 - 2500 nm in a single shot. We summarize
the main characteristics of the instrument and present its performances as measured during commissioning and
the first months of science operations.

KMOS is a near-infrared multi-object integral-field spectrometer which is one of a suite of second-generation
instruments under construction for the VLT. The instrument is being built by a consortium of UK and German
institutes working in partnership with ESO and is now in the manufacture, integration and test phase. In this paper
we present an overview of recent progress with the design and build of KMOS and present the first results from the
subsystem test and integration.

The SPHERE is an exo-solar planet imager, which goal is to detect giant exo-solar planets in the vicinity of bright stars
and to characterize them through spectroscopic and polarimetric observations. It is a complete system with a core made
of an extreme-Adaptive Optics (AO) wavefront correction, a pupil tracker and diffraction suppression through a variety
of coronagraphs. At its back end, a differential dual imaging camera and an integral field spectrograph (IFS) work in the
Near Infrared (NIR) Y, J, H and Ks bands (0.95 - 2.32&mu;m), and a high resolution polarization camera covers the optical
range (0.6 - 0.9 &mu;m). The IFS is a low resolution spectrograph (R~50) working in the near IR (0.95-1.65 microns), an
ideal wavelength range for the detection of giant planet features. In our baseline design the IFU is a new philosophy
microlens array of about 145x145 elements designed to reduce as much as possible the cross talk when working at
diffraction limit. The IFU will cover a field of view of about 1.7 x 1.7 square arcsecs reaching a contrast of 10<sup>-7</sup>,
providing a high contrast and high spatial resolution "imager" able to search for planet well inside the star PSF.

MATISSE is foreseen as a mid-infrared spectro-interferometer combining the beams of up to four UTs/ATs of the Very
Large Telescope Interferometer (VLTI) of the European Southern Observatory. The related science case study
demonstrates the enormous capability of a new generation mid-infrared beam combiner.
MATISSE will constitute an evolution of the two-beam interferometric instrument MIDI. MIDI is a very successful
instrument which offers a perfect combination of spectral and angular resolution. New characteristics present in
MATISSE will give access to the mapping and the distribution of the material (typically dust) in the circumstellar
environments by using a wide mid-infrared band coverage extended to L, M and N spectral bands. The four beam
combination of MATISSE provides an efficient UV-coverage : 6 visibility points are measured in one set and 4 closure
phase relations which can provide aperture synthesis images in the mid-infrared spectral regime.

CRIRES is a cryogenic, pre-dispersed, infrared Echelle spectrograph designed to provide a nominal resolving
power &nu;/&Delta;&nu; of 10<sup>5</sup> between 1000 and 5000 nm for a nominal slit width of 0.2". The CRIRES installation at
the Nasmyth focus A of the 8-m VLT UT1 (Antu) marks the completion of the original instrumentation plan
for the VLT. A curvature sensing adaptive optics system feed is used to minimize slit losses and to provide 0.2"
spatial resolution along the slit. A mosaic of four Aladdin InSb-arrays packaged on custom-fabricated ceramic
boards has been developed. It provides for an effective 4096 &times; 512 pixel focal plane array to maximize the free
spectral range covered in each exposure. Insertion of gas cells is possible in order to measure radial velocities with
high precision. Measurement of circular and linear polarization in Zeeman sensitive lines for magnetic Doppler
imaging is foreseen but not yet fully implemented. A cryogenic Wollaston prism on a kinematic mount is already
incorporated. The retarder devices will be located close to the Unit Telescope focal plane. Here we briefly recall
the major design features of CRIRES and describe the commissioning of the instrument including a report of
extensive testing and a preview of astronomical results.

Recently ESO has commissioned the HAWK-I camera which is equipped with a 2&times;2 mosaic of &#955;c~ 2.5 µm HAWAII-2RG arrays. The arrays have high quantum efficiency and achieve photon shot noise limited performance on the telescope. Using reference pixels it can be shown that the readout noise for most arrays is limited by the MBE grown
HgCdTe material and not by the multiplexer or the data acquisition chain. Results obtained with the guide window of the
HAWAII-2RG multiplexer will be presented. Inter-channel crosstalk and fringing in the detector substrate will be
discussed. The dynamic range of detectors can be expanded by applying threshold limited integration (TLI) to the
follow-up-the-ramp nondestructive sampling scheme. For substrate removed arrays a calibration technique based on the
X-ray emission of Fe<sup>55</sup> will be discussed.

Teledyne Imaging Sensors (TIS) has developed a new CMOS device known as the SIDECAR application-specific
integrated circuit (ASIC). This single chip provides all the functionality of FPA drive electronics to operate visible and
infrared imaging detectors with a fully digital interface. At the last SPIE conference we presented test and performance
results of a Teledyne 2K&times;2K silicon PIN diode array hybridized to a Hawaii-2RG multiplexer, the Hybrid Visible
Silicon Imager (HyViSI). This detector was read out with the ESO standard IR detector controller IRACE, which
delivers detector limited performance. We have now tested the H2RG HyViSI detector with the new TIS SIDECAR
ASIC in 32 channel readout mode at cryogenic temperatures. The SIDECAR has been evaluated down to 105 Kelvin
operating temperature and performance results have been compared to those obtained with external electronics. We find
that the SIDECAR ASIC provides performance equal to optimized external electronics.

The CALICO sensor is a pathfinder for the development of the future infrared high speed low noise detectors for AO.
Low readout noise at high readout speed is accomplished by high gain and signal processing circuitry under each pixel.
The high gain makes the detector very susceptible to instability if the system noise is too high. Lnpix3, the most
promising structure, has a pixel gain of 400. In this paper we will report on test results and different measures we had to
take getting the detector to work.

The detector is a critical component of any Adaptive Optics WaveFront Sensing (AO WFS) system. The required
performance combination of fast frame rate, high quantum efficiency, low read noise and dark signal, number and size
(24-50 &mu;m) of pixels pushes detector technology to the edge such that in many cases custom detector developments are
required. This paper examines the roadmap of optical and infrared detectors by reviewing; detectors that are currently
available and/or are in use in current instruments, detectors that are under development and will be used in future
instruments on existing telescopes, and the requirements and status of new detectors whose development are critical for
the success of the next generation of extremely large telescopes (E-ELT, GMT, and TMT). In addition, the paper will
report on the AO WFS detector development and testing programs currently under way at ESO.

X-shooter is a new high-efficiency spectrograph observing the complete spectral range of 300-2500 nm in a single
exposure, with a spectral resolving power R>5000. The instrument will be located at the Cassegrain focus of one of the
VLT UTs and consists of three spectrographs: UV, VIS and Near-IR. This paper addresses the design, hardware
realization and performance of the Near-IR spectrograph of the X-Shooter instrument and its components.
Various optical, mechanical and cryogenic manufacturing and verification techniques are discussed. The cryogenic
performance of replicated light weight gratings is presented. Bare aluminium mirrors are produced and polished to
optical quality to preserve high shape accuracy at cryogenic conditions. Their manufacturing techniques and
performance are both discussed. The cryogenic collimator and dispersion boxes, on which the optical components are
mounted, feature integrated baffles for improved stiffness and integrated leaf springs to reduce tension on optical
components, thereby challenging 5 axis simultaneous CNC milling capabilities. ASTRON Extreme Light Weighting is
used for a key component to reduce the flexure of the cryogenic system; some key numbers and unique manufacturing
experience for this component are presented. The method of integrated system design at cryogenic working temperatures
and the resulting alignment-free integration are evaluated. Finally some key lab test results for the complete NIR
spectrograph are presented.

HAWK-I is the newly commissioned High Acuity Wide-field K-band Imager at the ESO Very Large Telescope. It is a
0.9-2.5 micron imager with a field of view of 7.5&times;7.5 arcmin sampled at 106 mas with four Hawaii2RG detectors. It has
a full reflective design that was optimised for image quality and throughput.We present an overview of its performance as
measured during the commissioning and first science runs. In particular, we describe a detector read-out mode that allows
us to increase the useful dynamic range of the detector, and a distortion calibration resulting in &lt;5mas relative astrometry
across the field.

MIDIR is the proposed thermal/mid-IR imager and spectrograph for the European Extremely Large Telescope
(E-ELT). It will cover the wavelength range of 3 to at least 20 &mu;m. Designed for diffraction-limited performance
over the entire wavelength range, MIDIR will require an adaptive optics system; a cryogenically cooled system
could offer optimal performance in the IR, and this is a critical aspect of the instrument design. We present
here an overview of the project, including a discussion of MIDIR's science goals and a comparison with other
infrared (IR) facilities planned in the next decade; top level requirements derived from these goals are outlined.
We describe the optical and mechanical design work carried out in the context of a conceptual design study, and
discuss some important issues to emerge from this work, related to the design, operation and calibration of the
instrument. The impact of telescope optical design choices on the requirements for the MIDIR instrument is
demonstrated.

MIDIR is a combined thermal/mid-infrared imager and spectrograph for the European Extremely Large Telescope (EELT). It will operate in the infrared L, M, N, and Q-band to 20&#956;m with a goal to extend the wavelength coverage to 27&#956;m if the atmospheric properties of the site are sufficiently good. MIDIR will offer imaging and spectroscopic modes over a wide range in spectral resolution. MIDIR will be designed for diffraction limited performance, requiring an optimized, cryogenic adaptive optics (AO) system. The conceptual study of MIDIR is part of a suite of eight ELT instrument "small studies" partly funded by the EU [1]. The study is being performed by an international consortium of Leiden Observatory, Astron, MPIA, UK-ATC, and ESO. The high level instrument requirements for MIDIR have been directly derived from numerous important science cases. In this paper we discuss the science case for MIDIR, provide a summary of the technical specifications, discuss the requirements on the AO system, and estimate the sensitivity in various observing modes. More technical details on the instrument are given in a parallel paper at this conference [2].

HAWK-I is a new wide-field infrared camera under development at ESO. With four Hawaii-2RG detectors, a 7.5 arcminute square field of view and 0.1 arcsecond pixels, it will be an optimum imager for the VLT, and a major enhancement to existing and future infrared capabilities at ESO. HAWK-I will eventually make use of ground-layer AO achieved through a deformable secondary mirror/laser guide star facility planned for the VLT.

A MIR instrumentation study for a European ELT has been performed by a Dutch consortium led by the Leiden Observatory (The Netherlands) and the Max-Planck-Institut fur Astronomie in Heidelberg (Germany). MIR imaging and spectroscopic observational capabilities are compared to contemporary IR to sub-millimeter facilities, especially concentrating on the MIR-capabilities of JWST(MIRI). Our best effort calculation of the sensitivity for both MIR imager and spectrograph indicate a huge discovery potential in numerous areas from our planetary system to the high redshift Universe (see [6269-75] during this conference). Here we concentrate on the technical aspects of such an instrument, offering diffraction limited direct imaging capabilities over the wavelength range from 3.5&#956;m up to 20&#956;m or even 27&#956;m, as well as medium to high resolution spectroscopy for the same wavelength range. To make use of the extreme spatial resolution, the spectrograph is planned to include an integral field unit.

KMOS is a near-infrared multi-object integral field spectrometer which has been selected as one of a suite of second-generation instruments to be constructed for the ESO VLT in Chile. The instrument will be built by a consortium of UK and German institutes working in partnership with ESO and is currently at the end of its preliminary design phase. We present the design status of KMOS and discuss the most novel technical aspects and the compliance with the technical specification.

This paper presents the integration and first results for the CAMCAO NIR camera. The camera was built
for the ESO Multi-conjugate Adaptive optics Demonstrator, where it is presently operating, to evaluate the
feasibility of this Adaptive Optics technique. On a second phase it will work directly at the Nasmyth focus of the
VLT. CAMCAO is a high resolution, wide field of view NIR camera, that is using the 2k×2k HgCdTe HAWAII-
2 infrared detector from Rockwell Scientific, controlled by the ESO IRACE system. The camera operates in
the near infrared region between 1.0 &#956;m and 2.5 &#956;m wavelength using an eight position filter wheel with J, H,
K', K-continuum and Br&#947; filters. Both the integration experience and the results obtained in the mechanical,
vacuum, cryogenics and optical tests are presented, including all relevant parameters in the ESO specifications.
The requirement of mechanical stiffness together with light weight was achieved yielding a total weight of less
than 90 Kg. The camera fulfills both cryogenic and vacuum stability requirements. The temperature within
the detector is maintained at 80K by an accurate control loop, ensuring mK stability, after cooling down the
detector at a rate kept below 0.5 K/min. The optical performance tests were made using a Fizeau interferometer
both for the individual optical components and complete setup. The infrared optical validation measurements
were performed by re-imaging a point source in the camera focal plane and measuring the PSF with the detector.
The computed Strehl ratio reached 95% in the central region of the FoV, with values larger than 90% in a area
covering 88% of the focal plane.

For the past 25 years Charge Coupled Devices (CCDs) have been used as the preferred detector for ground based astronomy to detect visible photons. As an alternative to CCDs, silicon-based hybrid CMOS focal plane array technology is evolving rapidly. Visible hybrid detectors have a close synergy with IR detectors and are operated in a similar way. This paper presents recent test results for a Rockwell 2K x 2K silicon PIN diode array hybridized to a Hawaii-2RG multiplexer, the Hybrid Visible Silicon Imager (HyViSI). Since the capacitance of the integrating node of Si-PIN diodes is at least a factor of two smaller than the capacitance of the Hawaii-2RG IR detector pixel, lower noise was expected. However, those detectors suffer from interpixel capacitance which introduces an error to the value of the conversion factor measured with the photon transfer method. Therefore QE values have been overestimated by almost a factor of two in the past. Detailed test results on QE, noise, dark current, and other basic performance values as well as a discussion how to interpret the measured values will be presented. Two alternative methods, direct measurement of the nodal capacity and the use of Iron-55 X-rays to determine the actual nodal capacitance and hence the conversion factor will be briefly presented. PSF performance of this detector was analyzed in detail with an optical spot and single pixel reset measurement.

Since adaptive optics on large telescopes provides almost diffraction limited resolution, Nyquist sampling of moderate
fields requires large format arrays. Because of limited substrate sizes there is a tendency to shrink the pixel size to extend
the array format beyond 2Kx2K. However, with smaller pixel sizes the coupling capacitance between neighboring pixels
becomes more important and its effect on performance and basic parameters of large format arrays has to be analyzed.
Therefore, techniques to measure the effect of the coupling capacitance on the conversion gain will be presented. The
capacitance comparison method and the autocorrelation technique will be discussed and compared quantitatively. It will
be shown that the "noise squared versus signal" method which is in common use to obtain the conversion gain, can only
be applied for negligible interpixel capacitance. The X-ray decay of Fe55 is a well established calibrator for silicon and
can be applied to Si-PIN diode arrays in order to verify the different methods. Finally, a new technique called single
pixel reset will be presented, which directly measures the impulse response or point spread function generated by the
inter-pixel capacitance. The measured PSF impulse response can be used for the deconvolution of images to compensate
the degradation of spatial resolution induced by the interpixel capacitance. The difference of interpixel capacitance
measured in infrared hybrid arrays and Si-PIN diode arrays hybridized to the same multiplexer will be discussed.
Keywords:, interpixel capacitance, conversion gain, point spread function, single pixel reset, CMOS hybrid, Hawaii-
2RG, HgCdTe, Si-PIN, HyViSI.

CRIRES is a cryogenic, pre-dispersed, infrared echelle spectrograph designed to provide a resolving power lambda/(Delta lambda) of 10<sup>5</sup> between 1 and 5mu m at the Nasmyth focus B of the 8m VLT unit telescope #1 (Antu). A curvature sensing adaptive optics system feed is used to minimize slit losses and to provide diffraction limited spatial resolution along the slit. A mosaic of 4 Aladdin~III InSb-arrays packaged on custom-fabricated ceramics boards has been developed. This provides for an effective 4096x512 pixel focal plane array, to maximize the free spectral range covered in each exposure. Insertion of gas cells to measure high precision radial velocities is foreseen. For measurement of circular polarization a Fresnel rhomb in combination with a Wollaston prism for magnetic Doppler imaging is foreseen. The implementation of full spectropolarimetry is under study. This is one result of a scientific workshop held at ESO in late 2003 to refine the science-case of CRIRES. Installation at the VLT is scheduled during the first half of 2005. Here we briefly recall the major design features of CRIRES and describe its current development status including a report of laboratory testing.

X-shooter is a single target spectrograph for the Cassegrain focus of one of the VLT UTs. It covers in a single exposure the spectral range from the UV to the H band with a possible extension into part of the K band. It is designed to maximize the sensitivity in this spectral range through the splitting in three arms with optimized optics, coatings, dispersive elements and detectors. It operates at intermediate resolutions (R=4000-14000, depending on wavelength and slit width) sufficient to address quantitatively a vast number of astrophysical applications while working in a background-limited S/N regime in the regions of the spectrum free from strong atmospheric emission and absorption lines. The small number of moving functions (and therefore instrument modes) and fixed spectral format make it easy to operate and permit a fast response. A mini-IFU unit (1.8" x 4") can be inserted in the telescope focal plane and is reformatted in a slit of 0.6"x 12" .The instrument includes atmospheric dispersion correctors in the UV and visual arms. The project foresees the development of a fully automatic data reduction package. The name of the instrument has been inspired by its capability to observe in a single shot a source of unknown flux distribution and redshift. The instrument is being built by a Consortium of Institutes from Denmark, France, Italy and the Netherlands in collaboration with ESO. When it operation, its observing capability will be unique at very large telescopes.

The CAMCAO instrument is a high resolution near infrared (NIR) camera conceived to operate together with the new ESO Multi-conjugate Adaptive optics Demonstrator (MAD) with the goal of evaluating the feasibility of Multi-Conjugate Adaptive Optics techniques (MCAO) on the sky. It is a high-resolution wide field of view (FoV) camera that is optimized to use the extended correction of the atmospheric turbulence provided by MCAO. While the first purpose of this camera is the sky observation, in the MAD setup, to validate the MCAO technology, in a second phase, the CAMCAO camera is planned to attach directly to the VLT for scientific astrophysical studies. The camera is based on the 2kx2k HAWAII2 infrared detector controlled by an ESO external IRACE system and includes standard IR band filters mounted on a positional filter wheel. The CAMCAO design requires that the optical components and the IR detector should be kept at low temperatures in order to avoid emitting radiation and lower detector noise in the region analysis. The cryogenic system inclues a LN2 tank and a sptially developed pulse tube cryocooler. Field and pupil cold stops are implemented to reduce the infrared background and the stray-light. The CAMCAO optics provide diffraction limited performance down to J Band, but the detector sampling fulfills the Nyquist criterion for the K band (2.2mm).

HAWK-I (High Acuity, Wide field K-band Imaging) is a 0.9 &#956;m - 2.5 &#956;m wide field near infrared imager designed to sample the best images delivered over a large field of 7.5 arcmin x 7.5 arcmin. HAWK-I is a cryogenic instrument to be installed on one of the Very Large Telescope Nasmyth foci. It employs a catadioptric design and the focal plane is equipped with a mosaic of four HAWAII 2 RG arrays. Two filter wheels allow to insert broad band and narrow band filters. The instrument is designed to remain compatible with an adaptive secondary system under study for the VLT.

VLT instruments increasingly require high sensitivity large format focal planes. Adaptive optics combined with multiple integral field units feeding high resolution spectrographs drive the pixel performance as well as the array format. Three VLT instruments, the wide field imager Hawk-I and the integral field spectrographs SINFONI and KMOS will be equipped with MBE-grown HgCdTe Hawaii-2RG arrays, which have a cut-off wavelength of 2.5 micron. The Hawaii-2RG array was originally developed for the near infrared camera of JWST having a cut-off wavelength of 5 micron. The Hawaii-2RG multiplexer is one of the most advanced readout architectures offering a large variety of operating modes. A special 32 channel package has been developed which allows reading out all 32 output channels of the detector in parallel. Symmetric cryogenic CMOS operational amplifiers are placed next to the focal plane instead of using ASIC’s which are not yet available. The internal bus of the detector is accessed directly, bypassing the on-chip buffer amplifier. Noise performance employing different techniques of using reference pixels is discussed. Basic performance characteristics of the Hawaii-2RG arrays will be presented. Unlike LPE arrays, which lose quantum efficiency at lower temperatures, MBE arrays with &#955;<sub>c</sub> = 2.5 &#956;m do not show this effect. However, the MBE arrays under test still suffer from persistence.

The detector mounted in the VLTI fringe sensor FINITO is a 256x256 HgCdTe array with a cut-off wavelength of 1.9 micron. The same arrays having cut-off wavelengths of 2.5 micron will be used in the tip tilt sensor IRIS and the PRIMA instrument of the VLT interferometer. The arrays are part of an active control loop with integration times as short as a few hundred microseconds. The fringe tracker FINITO uses only 7 pixels of the array. To take advantage of the four parallel channels of the PICNIC multiplexer, the pixels illuminated in each quadrant are positioned at the same location within the quadrants. A noise analysis of the PICNIC array shows that the main sensitivity limitation of the array is contained in the low frequency part of the noise power spectrum. Similar behaviour has been observed with other infrared arrays. In an effort to optimize the unit cell pixel buffer to achieve high speed and low noise, a prototype multiplexer is being developed at Rockwell for adaptive optics. However, low frequency noise may still be the limiting factor dominating the noise performance of infrared arrays. To overcome this noise barrier, detector architectures have to be envisaged which should allow double correlated sampling on shorter time scales than a full exposure. This might be accomplished by some kind of gate in the IR material which allows charge to be shifted from an integrating well in the infrared pixel to a small sensing node capacitance of the multiplexer unit cell buffer.

For the high-resolution IR Echelle Spectrometer CRIRES (1-5 &mu;m range), to be installed at the VLT in 2005, ESO is developing a 512 x 4096 pixels focal plane array mosaic based on Raytheon Aladdin III InSb detectors with a cutoff wavelength of 5.2 microns. To fill the useful field of 135 mm in the dispersion direction and 21 mm in the spatial direction and to maximize simultaneous spectral coverage, a mosaic solution similar to CCD mosaics has been chosen. It allows a minimum spacing between the detectors of 264 pixels. ESO developed a 3-side buttable mosaic package for both the Aladdin II and Aladdin III detectors which are mounted on multilayer co-fired AlN ceramic chip carriers. This paper presents the design of the CRIRES 512 x 4096 pixel Aladdin InSb focal plane array and a new test facility for testing mosaic focal planes under low flux conditions.

CRIRES is a cryogenic, pre-dispersed, infrared echelle spectrograph designed to provide a resolving power of 10<sup>5</sup> between 1 and 5 &mu;m at a Nasmyth focus of one of the 8m VLT telescopes. A curvature sensing adaptive optics sytem feed is used to minimize slit losses and a 4096x512 pixel mosaic of Aladdin arrays is being developed to maximixe the free spectral range covered in each order. Insertion of gas cells to measure high precision radial velocities is foreseen and the possibility of combining a Fresnel rhomb with a Wollaston prism for magnetic Doppler imaging is under study. Installation at the VLT is scheduled during the second half of 2004. Here we briefly recall the major design features of CRIRES and describe its current development status.

CONICA has been developed by a German consortium under an ESO contract, to serve together with the VLT adaptive optics system NAOS as a high resolution multimode NIR camera and spectrograph. We report on final laboratory performance tests carried out during the integration period with the adaptive optics. Apart from an outline of the capabilities of this multimode instrument such as high resolution imaging, spectroscopy, Fabry-Perot and a sophisticated internal flexure compensation, we will turn our attention to a detailed examination of the detector characteristics to fully exploit the potential of the ALADDIN array.

The Adaptive Optics NIR Instrument NAOS-CONICA has been commissioned at the VLT (UT4) between November 2001 and March 2002. After summarizing the observational capabilities of this multimode instrument in combination with the powerful AO-system, we will present first on sky results of the instrumental performance for several non-direct imaging modes: High spatial resolution slit-spectroscopy in the optical and thermal NIR region has been tested. For compact sources below 2 arcsec extension, Wollaston prism polarimetry is used. For larger objects the linear polarization pattern can be analyzed by wire grids down to the diffraction limit. Coronographic masks are applied to optimize imaging and polarimetric capabilities. The cryogenic Fabry-Perot Interferometer in combination with an 8m-telescope AO-system is shown to be a powerful tool for imaging spectroscopy (3D-scans).

Only two months ago, in June 2002, a workshop on scientific detectors for astronomy was held in Waimea, where for the first time both experts on optical CCD's and infrared detectors working at the cutting edge of focal plane technology gathered. An overview of new developments in optical detectors such as CCD's and CMOS devices will be given elsewhere in these proceedings. This paper will focus on infrared detector developments carried out at the European Southern Observatory ESO and will also include selected highlights of infrared focal plane technology as presented at the Waimea workshop. Three main detector developments for ground based astronomers are currently pushing infrared focal plane technology. In the near infrared from 1 to 5 &mu;m two technologies, both aiming for buttable 2K x 2K mosaics, will be reviewed, namely InSb and HgCdTe grown by LPE or MBE on Al<sub>2</sub>O<sub>3</sub>, Si or CdZnTe substrates. Blocked impurity band Si:As arrays cover the mid infrared spectral range from 8 to 28 &mu;m. Since the video signal of infrared arrays, contrary to CCD's, is DC coupled, long exposures with IR arrays are extremely susceptible to drifts and low frequency noise pick-up down to the mHz regime. New techniques to reduce thermal drifts and suppress low frequency nosie with on-chip reference pixels will be discussed. The need for the development of small format low noise sensors for adaptive optics and interferometry will be pointed out.

The VIRMOS consortium of French and Italian Institutes is manufacturing 2 wide field imaging multi-object spectrographs for the European Southern Observatory Very Large Telescope, with emphasis on the ability to carry over spectroscopic surveys of large numbers of sources. The Visible Multi-Object Spectrograph, VIMOS, is covering the 0.37 to 1 micron wavelength domain, with a full field of view of 4 by 7 by 8 arcmin<SUP>2</SUP> in imaging and MOS mode. The Near IR Multi-Object Spectrograph, NIRMOS, is covering the 0.9 to 1.8 microns wavelength range, with afield of view 4 by 6 by 8 arcmin<SUP>2</SUP> in MOS mode. The spectral resolution for both instrument scan reach up to R equals 5000 for a 0.5 arcsec wide slit. Multi-slit masks are produced by a dedicated Mask Manufacturing Machine cutting through thin Invar sheets and capable of producing 4 slit masks approximately 300 by 300 mm each with approximately slits 5.7 mm long in less than one hour. Integral field spectroscopy is made possible in VIMOS by switching in the beam specially build masks fed by 6400 fibers coming form a 54 by 54 arcsec<SUP>2</SUP> integral field head with a 80 by 80 array of silica micro-lenses. NIRMOS has a similar IFS unit with a field of 30 by 30 arcmin<SUP>2</SUP>. These instruments are designed to offer very large multiplexing capabilities. In MOS mode, about 1000 objects can be observed simultaneously with VIMOS, with a S/N equals 10 obtained on galaxies with I equals 24 in one hour, and approximately 200 objects can be observed simultaneously with NIRMOS, with a S/N equals 10 obtained don galaxies with J equals 22, H equals 20.6 in 1h at R<SUB>eq</SUB> equals 200. We present here the status of VIMOS, currently under final integration, with expected first light in the summer 2000, together with the final design of NIRMOS presented at the Final Design Review. The VLT-VIRMOS deep redshift survey of more with the final design of NIRMOS presented at the Final Design Review. The VLT-VIRMOS deep redshift survey of more than 150000 galaxies over the redshift range 0 &lt; z &lt; 5 will be undertaken based on 120 guaranteed nights awarded to the project.

The first VLT IR instrument, ISAAC, was installed at the 8 meter Antu telescope in 1998. Experience and results with both InSb and HgCdTe large format arrays will be reported. Effects limiting the performance and strategies to partially overcome these limitations will be discussed.

Instrument platforms like the VLT represent a new challenge to IR focal plane technology. Since the large telescope diameter and the improved image quality provided by adaptive optics reduce the pixel scale, larger array formats are needed. To meet this challenge ESO is participating in development programs for both InSb and HgCdTe large format arrays. To cover the spectral region of 1 to 5 micron ESO has funded a foundry run at SBRC to produce 1024 X 1024 InSb arrays, which will be installed in ISAAC, the IR Spectrometer and Array Camera built for the VLT. Since the delivery of the 1K X 1K InSb array is delayed, the test results obtained with a 256 X 256 InSb array and the application of off chip cryogenic amplifiers to InSb detectors will be discussed. Results obtained with a (lambda) <SUB>c</SUB> equals 2.5 micrometers Rockwell 1024 X 1024 HgCdTe array will be presented, where an off chip cryogenic operational amplifier was used yielding a rms read noise of 3 electrons. Sensitivity profiles of individual pixels have been measured with a single mode IR fiber. Limitations of PACE 1 technology, such as persistence, will be discussed. First results with the 1K X 1K array, which was installed in SOFI, an IR focal reducer providing 1-2.5 micron imaging and long slit grism spectroscopy at the NTT telescope, will be presented. Advanced techniques of real time image sharpening will also be included. An outlook to the development of (lambda) <SUB>c</SUB> equals 2048 X 2048 HgCdTe array formats will be given. The optical layout of NIRMOS, a multi-object spectrograph for the VLT telescope, is base don the availability of 2K X 2K HgCdTe arrays.

The ESO IR detector high speed array control and processing electronic IRACE is designed as a modular system and supports readout and data processing of arrays with four as well as multiple output channels. In addition the system can handle multiple separate arrays and the data re routed to multiple processing chains. Detector front-ends are galvanically separated form data processing and system administration with fiberoptic links. Interfaces to different data processing systems for on-line data handling are implemented. The paper describes principles of system operation, and the achieved readout and on-line processing speeds.

For the next generation of instruments which will be used at 8 m telescopes large format arrays are needed. Better image quality obtained by adaptive optics requires sampling to higher spatial frequencies. The large field of these instruments increases the demand for array formats as large as 1024 by 1024 and beyond. For this reason ESO is committed to the development of megapixel infrared detectors. In a multimode instrument covering the 1 to 5 micrometer spectral range a detector has to fulfill very different requirements. For high resolution spectroscopy low dark current and read noise are required. For broad band thermal imaging a high well capacity is needed to reduce the speed required to read out the array before it saturates. This paper gives a status report of ESO's activities related to large format arrays. An ultrafast data acquisition system has been developed to read out large format arrays. The performance goal is to achieve shot noise limited operation in the wavelength region of lambda equals 1 to 5 micrometer. The array controller is capable of handling the high data rates generated in the thermal infrared. The design of the controller was mainly driven by the requirement to read out the 32 parallel video channels of the SBRC 1024 by 1024 InSb detector in 50 msec. The array controller can also cope with the low read noise required for flux levels of less than 1 photon/sec. A new test camera for large format arrays has also been built. First test results obtained with the Rockwell 1024 by 1024 HgCdTe array are presented. The noise and dark current performance will be discussed with regard to OH line suppression. Read speed requirements will be defined for advanced readout techniques of image sharpening applying on chip tracking in the multiple nondestructive readout mode.

Photovoltaic detectors for ground based astronomical applications have experienced dramatic improvements during the last decade. Both the array format has been increased and the pixel performance has improved and is approaching fundamental limits. In view of this development a detection limit for the photon flux of the ideal detector will be derived, depending only on the temperature and the impedance of the detector. It is shown, that this limit is approximated by state of the art infrared arrays for long on chip integrations. In a multimode instrument covering the 1 to 5 micrometers spectral range a detector has to fulfill very different requirements. For high resolution spectroscopy low darkcurrent and read noise are required. For broad band thermal imaging a high well capacity is needed to reduce the speed required to read out the array before it saturates. Different possibilities to increase the well depth of infrared arrays have been investigated. First, an extra capacity can be added to the gate of the source follower in the unit cell of the multiplexer. Alternatively, the pixel capacity can be increased by increasing the doping concentration of the detector diode. The third possibility is to apply a large reverse bias voltage. This requires exceptionally good low doped InSb junctions which can be operated at a reverse bias voltage of 1 volt.

A fiberoptic link with a transmission rate of 1 gigabit/s is used in the ESO IR data acquisition system. The link connects the detector front-end with a multiprocessor system, based on T9000 transputers. The link not only transmits data -- the architecture of the system allows distribution of data to the multiprocessor system in a flexible and simple way. The paper describes principles of link operation, why this speed is required, and briefly the components used.

A new non-destructive readout scheme for IR array detectors, which allows image sharpening by on chip tracking has been tested with the ESO IR array camera IRAC2. This camera is equipped with a large format NICMOS3 256*256 MCT array detector. The effect of the readout algorithm is equivalent to a first order wavefront correction of images degraded by atmospheric seeing. Correction is performed in real time for long on chip detector integrations. Results obtained at a 2.2 m telescope on the pre main sequence binary star S CrA, the Circinus galaxy and the cluster NGC3603 will be presented. Possible applications of this method at large 8 m telescopes will be discussed.

ESO has recently installed a new infrared array camera IRAC2 which is equipped with a large format NICMOS3 256*256 Hg<SUB>1-x</SUB>Cd<SUB>z</SUB>Te array detector. The performance of the instrument and the detector array will be discussed briefly. A new nondestructive readout scheme of the array will be presented which allows first order wavefront corrections of images degraded by atmospheric seeing. During the stare time the integration ramp of the detector signal is sampled every 100 msec. A regressional fit of the sample data points yields the slope of the integration ramp which is proportional to the flux received by a detector pixel. To this readout mode which is commonly used for IR arrays a small software module can be added to compensate the image motion of the observed object by shifting the nondestructively sampled images. This has the same effect as a tip tilt correction by an active optical element--but without the extra complexity of such a device. Lab tests and first results obtained at the telescope are presented.

The performance of a recently developed indium antimonide (InSb) two-dimensional multiplexed medium wavelength infrared (MWIR) hybrid focal plane array (FPA) is presented. The CMOS FET switch array multiplexer individually buffers each detector in a 64 x 64 element array through a source follower amplifier. This multiplexer was designed for demanding low-background, high sensitivity requirements. The detector array consists of InSb photodiodes spaced on 100 micron centers, bump bonded through indium columns to the silicon multiplexer, and is thinned for backside illumination. The array is responsive to radiation in the 1 to 5.5 micron region. The FPA has been demonstrated to have a near theoretical read-out noise performance of less than 500 electrons. The, charge storage capacity is approximately 4 million electrons giving a dynamic range of 78 dB. The device is linear to better than 99.95%over the lower 30% of its dynamic range, and greater than 90% over its total range, reflecting the capacitive discharge nature of the charge integration. Dark currents of less than 10 pA are obtained at 77K with reverse biases as great as 0.5V, and less than 0.2 fA at 25K. Quantum efficiency greater than seventy-five percent has been achieved at the peak wavelength. Functional element yields of 99% have been obtained.

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